1. Field of the Invention
The present invention relates to a solid oxide fuel cell (SOFC), and particularly to a solid oxide fuel cell having a (flat-plate) stack structure in which sheet bodies (may also be referred to as “single cells”) and support members (may also be referred to as the “interconnectors”) are stacked in alternating layers.
2. Background of the Invention
Conventionally, a solid oxide fuel cell having the above-mentioned stack structure has been known (refer to, for example, Japanese Patent Application Laid-Open (kokai) No. 2004-342584). In this case, the sheet body can be a fired body in which a solid electrolyte layer formed from zirconia, a fuel electrode layer, and an air electrode layer are arranged in layers such that the fuel electrode layer is formed on the upper surface of the solid electrolyte layer and such that the air electrode layer is formed on the lower surface of the solid electrolyte layer.
For each sheet body, a channel (fuel channel) of a fuel gas (hydrogen gas) is defined between the sheet body and the support member formed above the sheet body so as to be adjacent to the sheet body, while a channel (air channel) of a gas (air) containing oxygen is defined between the sheet body and the support member formed below the sheet body so as to be adjacent to the sheet body.
In the structure described above, a fuel gas is supplied to the fuel channel and air is supplied to the air channel with the temperature of the SOFC (specifically, sheet body) being raised and heated to a working temperature (e.g., 800° C.) of the SOFC. Thus, the fuel gas and air are brought into contact with the upper surface (fuel electrode layer) and the lower surface (air electrode layer) of each of the sheet bodies respectively, whereby electricity generating reaction (refer to the later-described Formulas (1) and (2)) is produced for each sheet body. As a result, the stack structure can serve as a cell. For convenience of description, the plane direction of the stacked sheet bodies (or support members) is merely referred to as “plane direction”, and the direction in which the sheet bodies and the support members are stacked (the direction vertical to the plane direction) is referred to as “stacking direction”.